Naturally occurring alpha-methylene-gamma-butyrolactones with tumor inhibiting activity are characterized by oxygen substituents near the lactone ring. With a view toward developing synthetic approaches to these oxygenated alpha-methylene-gamma-butyrolactones and to those having other common functional patterns, a number of cyclopropylcarbinyl derivatives will be prepared and their rearrangements investigated. It is anticipated that the rearrangements can be directed by the electronic effects of nearby functional groups and by neighboring group participation by more remote functional groups. The lactones thus prepared will be tested for biological activity. Possible approaches to the tumor inhibitor vernolepin are discussed.